Screen with spring supported vibratory drive



y 11, 1967 G- ERLENSTADT ET AL 3,330,411

SCREEN WITH SPRING SUPPORTED VIBRATORY DRIVE 2 Sheets-Sheet l Filed Dec. 14, 1964 w r m .6; WWW m J wmw m I mm mm n July 11, 1967 ERLENSTADT ET AL 3,330,411

SCREEN WITH SPRING SUPPORTED VIBRATORY DRIVE Filed Dec. 14, 1964 2 Sheets-Sheet 2 FIG.4. FIG.5.

mvsmons Giinter Erlensitidi 8: Harold Dfirner ATTORNEYS United States Patent 3,330,411 SCREEN WITH SPRIN G SUPPORTED VIBRATORY DRIVE Giinter Erlenstiidt and Harald Diirner, Remscheitl-Luttringhausen, Germany, assignors to Firma Rllewum Rheinische Werlrzeugand Maschinenfabrik G.rn.b.H., Remscheid-Luttringhausen, Germany Filed Dec. 14, 1964, Ser. No. 417,911 Claims priority, application Germany, Dec. 13, 1963, R 36,783 5 Claims. (Cl. 209257) The present invention relates to a sifting machine and more particularly to a sifting or screening machine wherein the screening box or screening frame is driven by means of an eccentric motor or an electromagnetic vibrator, in an oscillatory manner. In addition, the screen surface is driven by means of vibration generators, which generators are directly coupled with the screen surface and act thereupon in a direction perpendicular thereto.

This general type of screening machine is known in the prior art. One known machine ha an eccentric motor which causes the screening box to move in an oscillatory fashion, and a second eccentric motor, mounted on the screening box, which directly drives the screening surface via a tappet connected to and perpendicular to the surface, so that the screen surface is caused to vibrate in a direction normal to its surface.

Another known machine uses electromagnetic vibrators in place of the second eccentric motor driving the screening surface, each of which is provided with a tappet which is fixedly connected with the armature of the magnet above and while its other end is fastened to the screening surface.

In another machine known in the prior art, the electromagnetic vibrators have been eliminated, and the plungers effective upon the screen surface are resiliently suspended at the screening box frame. These plungers receive their driving pOWer from the vertically effective component of force generated by the eccentric motor which drives the screening frame.

The disadvantage of this last-mentioned machine is that the entire mass of the screening machine must be driven by the eccentric motor. This requires, on the one hand, a very heavy and large drive motor and, on the other hand, very sturdy and expensive base supports or foundations, to absorb the forces generated by the screening machine. Moreover, the screen surface which acts like a membrane, is likewise set into transverse vibrations automatically, due to the vertical component of the eccentric drive; these vibrations can combine with and subtract from the vertical vibrations caused by the vibrating tappets, in a manner which is uncontrollable. The vibrations of the screen surface have amplitudes which vary with position, the smallest of which occur in the vicinity of each of the points of support. These natural vibrations of the screen surface are additionally influenced in an irregular manner, by the materials placed on the screen to be sifted.

It is therefore an object of the present invention to render the vibration process which takes place on the screen surface in such machine controllable, utilizing the simplest construction and at the lowest cost.

It is a further object of the present invention to provide a screening machine which preserves the desirable features of prior art devices, while overcoming their deficencies.

It is another object of the present invention to provide a sifting machine wherein a single vibratory drive motor generates both transverse vibrations of the screen for sifting materials therethrough, and also provides longitudinal vibration for conveying the sifted or screened materials away.

3,330,411 Patented July 11, 1967 ice These objects and others are accomplished by connecting the mass carrying the drive with the stationary and fixedly mounted frame carrying the screen surface, or with its supporting structure, by means of balanced springs.

Furthermore, according to the invention, the mass carrying the drive is resiliently suspended from the rigid frame structure carrying the screen surface.

Additional objects and advantage of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 shows, in longitudinal section, a screening machine according to the present invention.

FIGURE 2 is a cross-sectional view of the structure of FIGURE 1, taken along the line 22.

FIGURE 3 is a longitudinal sectional view of a further embodiment of a screening machine, according to the present invention.

FIGURE 4 is a cross-sectional view of a structure shown in FIGURE 3, taken along the section 4-4.

FIGURE 5 is a cross-sectional View of still another embodiment of the present invention.

In one embodiment of the present invention, the mass carrying the drive has mounted on it, in resilient mountings, vibrating elements which act upon the screen in a direction normal to its surface, and which are attached to the screen surface.

According to another feature of the invention, the mass carrying the oscillatory drive is connected with the mass carrying the vibrating elements which drive the screen surface by means of tuned springs.

In another embodiment of the invention, the screen frame, which supports the screen along at least a portion of its periphery, is resiliently mounted with respect to the vibrating conveying chute, or vice versa, and a plurality of vibratin elements act upon the screen surface, which vibrating elements are distributed across the screen surface. These vibrating elements are resilient tappets and are directed vertically to the screen surface. They are excitable via the drive of the vibrating conveying chute, which also serves a the mass.

An advantageous feature of the invention is distinguished in that, in the structure described above, the vibrating elements effective upon the screen surface, are tuned to a common fundamental frequency.

Another advantageous feature of the present invention lies in that the vibrating elements effective upon the screen surface are resiliently mounted on the vibrating conveying chute.

In still another embodiment of the present invention the vibrating elements effective upon the screen surface are resiliently mounted to supports coupled to the screen frame.

A further feature of the present invention lies in that the spring elements carrying the screen frame have their axes aligned substantially in the direction in which the material which has been sifted is to be transported. This is accomplished by aligning the axes of these spring elements substantially along the direction of the oscillations of the vibrating conveying chute drive.

The present invention has made it possible to achieve eflicient operation with only a single fairly light weight drive, for example, an electromagnetic drive, both for generating the pulsating forces on the screen surface necessary for eiiicient screening, and for conveying the material on top of the screen that is in the conveying chute beneath the screen. This is achieved by virtue of the fact that the drive does not vibrate the whole screening machine, with all its mass (due to various equipment) but that only the chute receiving the goods from underneath the screen is driven, whereby the mass to be driven is relatively small.

' motions in the goods being screened which motions are enhanced by 'the only slightly inclined attitude of the screen surface.

The screen surface itself is normally carried by a stationary, rigid frame which does not vibrate, so that normal, or perpendicular vibrations of the screen surface are produced only by virtue of the normal directionality of the vibrating elements with respect to the screen surface; no natural vibrations of the screen surface can be set up other than those produced which are the ones produced by the vibrating elements.

Referring more specifically to the figures of the drawings, in FIGURES 1 and 2, a conveying chute 1 carries a drive 2 and is mounted, with respect to supporting struc ture 15, by means of springs 3. Above the conveying chute 1 a stationarily mounted screen frame 4 is provided for a screen 5. The frame 4 supports the screen 5 along at least a portion of its periphery and is rigidly con: nected with the supporting structure 15. Several vibrating elements 6 in the form'of tappets are distributed across the screen surface; they are fastened to the conveying chute 1 by means of springs 7 and to the screen5 by means of flanges 6a. These tappets are excited by the drive 2.

In the embodiment shown in FIGURES 3 and 4, the vibrating elements 6 are mounted by means of springs 7 on the mass 8, which is connected with the screen frame 4. Further, the screen frame 4 is supported with respect to the stationary support 15, by means of springs 3 and supports the conveying chute 1 by means of springs 9, the axes of which lie substantially parallel to the vibrating motion of the drive 2.

A feature of the invention illustrated in FIGURE 3 is the provision of two screen frames 4, 4 which are arrangedone behind the other, in series, and which support respectively, screens 5, 5 of different mesh size, the higher-positioned screen 5' having the small mesh aperture. Furthermore, the chute 1 has a separating wall 11 behind the outlet end 10.

In FIGURE 5, a hood 12 connected with the screen frame 4 serves as the moimting for the vibrating elements 6 and is itself supported by means of springs 9.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. A screening machine comprising, in combination:

screen means;

stationary frame means supporting said screen means and maintaining said screen means at a slight angle with respect to the horizontal;

vibration generating means;

a mass attached to said vibration generating means for carrying, and for being vibrated by, the latter; and spring means constituting the only means directly con- 4 meeting said mass with said stationary frame means; a support mass; a plurality of vibratory element operatively associated with said mass and tuned to a fundamental.

vibration frequency for transmitting forces from said mass to said screen means in a direction normal to said screen means, said vibratory elements being resiliently connected between said screen means and 1 said support mass; and tuned spring means connecting said mass to said support mass. Y 2. A screening machine as defined in claim 1, wherein said vibratory elements are resiliently mounted on'said support mass.

3. A screening machine as defined in claim 2, wherein said tuned spring means connecting said mass to said support mass are resilient predominantly in the direction in which the material to be screened is to be transported.

4. A screening machine as defined in claim 3, wherein said tuned springs connecting said mass to said support massare disposed such that their axes of extension are" means operatively connected to said vibration transmit ting elements for imparting vibrations thereto and forming a conveying chute beneath said screen means for receiving materials sifted through said screen means; vibratory drive means connected to said chute for causing said conveying chute to oscillate, which oscilla-, tion has 'a longitudinal component and a component in the direction defined by the normal to said screen means; and

tuned spring means constituting the only means connecting'said vibratory drive means in a supporting manner'to said stationary frame means, in consequence of which the component of the oscillation generated in the chute means along said normal cause the screen means to vibrate through said vibrationtransmitting elements.

References Cited 3 UNITED STATES PATENTS 1,621,564 3/1927 Sturtevant 209-347 1,845,373 2/1932 Weber 209 310 2,251,586 8/1941 Flint 209-36 X 2,481,131 9/1949 Lindsay 209-365 2,925,911 2/1960 Parks 209 415 X 3,063,546 11/1962 Sherwen 209-365 3,179,251 3/1965 Nickel 209 310 FOREIGN PATENTS 729,637 11/ 1942 Germany.

HARRY B. THORNTON, Primary Examiner. R. HALPER, Assistant Examiner. 

1. A SCREENING MACHINE COMPRISING, IN COMBINATION: SCREEN MEANS; STATIONARY FRAME MEANS SUPPORTING SAID SCREEN MEANS AND MAINTAINING SAID SCREEN MEANS AT A SLIGHT ANGLE WITH RESPECT TO THE HORIZONTAL; VIBRATION GENERATING MEANS; A MASS ATTACHED TO SAID VIBRATION GENERATING MEANS FOR CARRYING, AND FOR BEING VIBRATED BY, THE LATTER; AND SPRING MEANS CONSTITUTING THE ONLY MEANS DIRECTLY CONNECTING SAID MASS WITH SAID STATIONARY FRAME MEANS; A SUPPORT MASS; A PLURALITY OF VIBRATORY ELEMENTS OPERATIVELY ASSOCIATED WITH SAID MASS AND TUNED TO A FUNDAMENTAL VIBRATION FREQUENCY FOR TRANSMITTING FORCES FROM SAID MASS TO SAID SCREEN MEANS IN A DIRECTION NORMAL TO SAID SCREEN MEANS, SAID VIBRATORY ELEMENTS BEING RESILIENTLY CONNECTED BETWEEN SAID SCREEN MEANS AND SAID SUPPORT MASS; AND TUNED SPRING MEANS CONNECTING SAID MASS TO SAID SUPPORT MASS. 